Operational mistakes which occur when trains are run on a rail network, such as signalling system failures or driver errors, generally involve interactions between network infrastructure and on-board train systems. It is increasingly popular to use Geographic Information Systems (GIS) to analyse railway operation and vehicle errors/malfunctions. In such a system a GIS tool or function maps train operation events according to recorded locations of the events. The locations can be recorded by an on-board locator, such a Global Positioning System (GPS) device or odometer information, or by a ground-side system.
However, the accuracy of event mapping has limitation due to locator accuracy, map accuracy and event record timing accuracy. For example, the measurement accuracy of GPS can vary from 5 to 100 m. Particularly in the vicinity of stations, the locations of reference points (typically specific items of network infrastructure) can have similar or smaller spacings. Separate from measurement accuracy error, the recording of train events may itself have time delays caused by the finite and variable times required, for example, data acquisition, processing, communication etc. Due to these issues, location measurement timings and event occurrence timings can vary, causing inaccuracies in the recorded locations of events.
Because of these limitations, an operator (such as a user of condition monitoring and data analysis systems) can have difficulties understanding relationships between events and infrastructure. In particular, if a mapping error is large, the operator may not recognize that an event has occurred at a certain item of infrastructure rather than just somewhere close to it.
One option is simply to improve location measurement accuracies, but this can be costly and time-consuming to implement. Thus it would be desirable to provide alternative approaches to improve event mapping on a railway network.